I too have the itching on my mid back and have had it since I got the first Covid Vaccine over three years ago. I only got the first two shots (thank the Lord) but the itching is horrible. It comes when I am stressed, get hot, wear something that is irritating to my skin, or sometimes just out of the blue. I don't think I have a rash just a few bumps that I can feel when I reach my hand back. I also get really itchy on my head. I also have switched shampoo's, body wash, laundry soaps, lotions, etc to all things pure. I have been diagnosed with Chronic Spontaneous Urticaria. I have been tested for Mastocytosis (which came out negative) because my tryptase levels are so high and if I get bit by any type of Spyder, bug, mosquito, or Bee I have a severe reaction due to the High Tryptase levels that become even higher. My allergist said that you can have Spontaneous Chronic Urticaria without having a rash, that it can be internal. It is no fun itching all the time. I have been getting injections of Xolair monthly for at least a year and they have helped but this time they injected one shot into my stomach rather than one in each arm and it didn't work at all.